Apicomplexa or sporozoa are single-cell organisms which are parasites of vertebrates or of invertebrates. These parasites can cause various pathological conditions.
For example, coccidiosis, which is an intestinal disease caused by several distinct species of the Eimeria protozoan, is a parasitic infection which is economically significant for the poultry industry throughout the world.
They are generally treated with drugs which are antibiotics of the sulfamide category. However, the use of this chemoprophylaxis is not without drawbacks, owing in particular to the emergence of drug-resistant Eimeria strains and to the complicated interaction between coccidiosis parasites and clostridial infections. Furthermore, the regulations regarding drugs are ever increasing in animal production.
Because of the complexity of the host's immunity and of the lifecycle of the parasites, it proves to be particularly difficult to develop new strategies for intervention or new vaccines against apicomplexa. 
There is at the time no totally effective vaccine against these infections. The current tendency is therefore to use vaccines based on live parasites to control coccidiosis. At least ten vaccines of this type are commercially available worldwide. All these vaccines have recourse to infected live oocysts in order to produce a real infection which is intended to trigger a natural immunization that protects poultry.
This vaccination technique has the major drawback that live oocysts can be produced only by chickens, which requires a lot of work and involves numerous manipulations.
An alternative to vaccines of this type consists in using recombinant-protein vaccines against coccidiosis, said recombinant protein being for instance profilin which is an immunogenic protein of Eimeria. Recombinant vaccinations using profilin by subcutaneous immunization in young chickens or by immunization of embryos have induced a certain protection against avian coccidiosis. However, protein vaccines have a limited immunogenicity and their efficacy as a vaccine for reducing production losses due to coccidiosis is lower than that of the conventional coccidiostats and than the live oocyst-based vaccine. In any event, in order to improve the efficacy of the vaccines, various strategies have been examined, including adjuvants and cytokines.
Recent scientific publications show the direct effects of phytonutrients derived from plants on the genes involved in innate host immunity in poultry. However, numerous phytonutrients exist naturally and, for those which have been studied, they can have completely different properties from one another. For example, among the phytonutrients used in the present invention, the following are found:                carvacrol is one of the most common components of essential oils, it has a wide antimicrobial activity, and it has been approved as a safe feed additive in the United States of America and in Europe;        cinnamaldehyde has shown antifungal, antipyretic, antioxidant, antimicrobial and larvicidal activity, in addition to modulating T cell differentiation;        pepper (Capsicum spp) reduces intestinal pro-inflammatory cytokine levels, it increases weight gain and reduces parasitic fertility in poultry infected with E. acervulina;         plants of the Curcuma genus, including C. longa, exhibit antioxidant and anti-inflammatory properties, and chicken macrophages treated with curcuma extracts have shown increased levels of mRNA encoding IL-6 and IFN-γ.        
One of the new drug-free approaches which has not been tested up until now is the combined strategy of using a vaccine with a nutrition-mediated dietary immunomodulation, in particular mediated by phytonutrients as nutritional supplements.